You're an adult (well, presumably you're over 18 anyway at this point, although some students who skipped a year might be younger), they can't tell your parents anything without your consent as your parents no longer have any right to that data.
As for attendance otherwise, usually if it's an issue it will be raised as and when by your personal tutor. If it's not come up yet then probably not a problem, just be mindful of it and don't let it become a problem. Remember they can withdraw you from a course for non-engagement, but usually this will be after they have made quite a few attempts at engaging with you to understand the situation (including e.g. personal tutor meetings etc).
Missing a couple of lectures here or there isn't the end of the world and it's expected that students will plan their own time and make reasoned judgements about how they are spending it. Generally though I would suggest going to lectures even if you're not motivated - just sit and "take it in" rather than focusing on making active notes if need be. You'll still pick up a lot in the process.
Note that if you're on a student visa I believe there are attendance requirements on certain visa types so this may come up and be an issue. If you're a home/UK student though that isn't a factor.